1. Field of the Invention
The invention relates to a light emitting diode load driving apparatus, and more particularly, to a light emitting diode load driving apparatus for reducing power loss during a power-off period and storing segmental dimming data.
2. Description of Related Art
The traditional light emitting diode (LED) load driving apparatus is generally composed of a control chip, a power switch, and circuits such as a plug-in circuit. In particular, the control chip can provide a driving signal to switch the power switch such that an LED can emit light based on a current generated by switching the power switch. With the current LED dimming technology, the conventional LED load driving apparatus uses pulse width modulation (PWM) dimming technology to achieve high contrast, wherein the dimming principle works by adjusting the length of the duty cycle of the PWM dimming signal and controlling the time ratio of the full-lit and full-dark LED to achieve the purpose of dimming.
Generally, in the application of LED lighting multi-segmental dimming, a voltage is provided to activate the LED driving apparatus such that the control chip is operated under the voltage. When the LED dimming is powered-off; the control chip needs the power provided by an external capacitor of the control chip to last through the power-off period of the LED. However, if the power of the capacitor is not enough for the control chip to last through the power-off period of the LED, the control chip will become inactivated and therefore the temporarily stored adjustment PWM dimming operation data (such as the brightness sequence of the LED) of the control chip will be lost. As a result, the LED driving apparatus cannot implement multi-segmental dimming operations. Traditionally, the external capacitor is generally increased to solve the problem, however the method not only increases manufacturing costs but also increases the area needed for the printed circuit board (PCB).